The theater world’s buzzing about Cameron Mackintosh’s “Les Misérables” movie. Not since “Chicago” has a film adaptation of a stage show generated this much excitement around Shubert Alley.

The other night at Sardi’s, a bunch of top producers and theater owners gathered around the second-floor bar to raise a holiday glass. The talk was of two things: how soft business is these days — and the “Les Miz” movie.

“I hear, right from the horse’s mouth, that it’s great,” one producer said.

The horse is, of course, Mackintosh himself, the irrepressible British impresario who’s said to own 75 percent of the stage musical, which has a worldwide gross of more than $3 billion.

Mackintosh has been hopscotching the globe — London, Tokyo, Los Angeles, New York — talking up the movie, and he’s over the moon about the reception it’s been getting at early screenings. I attended one last week and can report that the audience applauded the big numbers as if they were watching a live stage version — and they stood at the end.

I’ll leave the reviewing to my colleague Lou Lumenick, who’s seeing “Les Miz” next week, but let me put in a good word for Anne Hathaway, who plays Fantine.

Hathaway reportedly lost 25 pounds for the role. She is heart-breakingly thin as this poor woman who’s ground into oblivion by the cruel Paris of Victor Hugo.

And she sings the hell out of “I Dreamed a Dream,” with Herbert Kretzmer’s powerful English lyrics — “But the tigers come at night/With their voices soft as thunder.”

Alain Boublil, the show’s librettist, originally wrote the lyrics in French.

“Anne was reinventing the song from Day One,” says Boublil. “After Patti LuPone and Susan Boyle and the 200 other recordings of the song, she has found a completely new way into it.”

Hathaway has a very simple explanation for how she pulled it off: “I didn’t listen to Patti LuPone until after I sung it!”

The song is all the more powerful because Boublil switched its location. In the stage version, it comes after Fantine’s been let go from the factory. In the movie, it comes after she’s been raped.

“It is in a much more dramatic — and cinematic — place now,” Boublil says. “You feel you are digging inside her head, inside her soul.”

Boublil and Claude-Michel Schönberg, who wrote “Les Misérables” for a Paris production in 1980, began thinking about turning it into a movie 20 years ago. Alan Parker was going to direct and had even made several models of the set. But he got cold feet at the last minute about doing a sung-through movie. A few years later, however, he did “Evita” with Madonna.

“In the cinema, you don’t have an explanation for these things,” says Boublil. “Things go very well one day, and then one day, suddenly, they don’t. But I’m rather glad it didn’t happen then. I don’t think we knew exactly how to do it.”

A key decision director Tom Hooper made, with encouragement from Boublil and Schönberg, was to have the actors sing live during the shooting.

“There was a man in a glass booth on the set playing the piano,” says Boublil. “He was the only person in contact with the performers. They had an invisible earpiece so they could hear him. Because it is so intimate, they are expressing their real feeling, their inner thoughts. There is, I hope, a lack of artifice. You should forget that they are singing.”

Another benefit of delaying the movie 20 years was getting Hugh Jackman, who plays Jean Valjean.

“I always say that when we conceived the idea of turning ‘Les Misérables’ into a musical, Hugh Jackman was 6,” says Boublil. “Twenty years ago, we toyed with using famous actors, but there was no obvious choice. Hugh is the obvious choice.”